Problem: Simplify the following expression: $10\sqrt{28}$.
Explanation: First, try to factor a perfect square out of the radical. $= 10\sqrt{28}$ $= 10\sqrt{4 \cdot 7}$ Separate the radical and simplify. $= 10\sqrt{4} \cdot \sqrt{7}$ $= 10 \cdot 2 \cdot \sqrt{7}$ $= 20\sqrt{7}$